North Falkland well yields oil at commercial rates

By OGJ editorsHOUSTON, June 27 -- An appraisal well at Sea Lion field in the North Falkland basin has produced oil at commercially viable rates, said Rockhopper Exploration PLC.

The 14/10-5 appraisal well stabilized at 5,508 stb/d and achieved a maximum stabilized rate of 9,036 stb/d.

A total section of 86 m, incorporating 79 m of reservoir, was perforated at 2,379-2,465 m measured depth over the Sea Lion main fan complex. No lower fan sands were perforated on this test.

The well produced for a main 48-hr period at a stabilized rate of 5,508 stb/d of oil and 940 Mscfd of gas with 783 psi flowing wellhead pressure on a 48/64-in. choke with a gas-oil ratio of 170 scf/stb.

The well was produced through a separator under artificial lift by means of a downhole electric submersible pump. The producing wellhead temperature was 62° C., sharply higher than that achieved during the test of well 14/10-2, and demonstrates the highly effective nature of the vacuum insulated tubing (VIT) used during the test at 14/10-5. No wax inhibitors or pour point suppressants were used, and no water or hydrogen sulfide were produced during the test.

During a second main test period the final maximum rate was 9,036 stb/d at 625 psi wellhead pressure on a fixed 1-in. choke over a 2-hr period before the well was shut-in for a final build-up and injectivity tests. The GOR during this test period was 153 scf/stb. Surface and downhole crude oil samples were collected for analysis.

Downhole mini drillstem tests were also performed on two of the three sands making up the 14 m of net pay encountered in the well, which form part of the lower fan. These two sands had net pay of 8 m and 4.5 m.

Interpretation of the results of the mini DSTs indicate that these two sands could have contributed an additional 800 stb/d flow rate using the same test techniques (artificial lift by ESP and thermal insulation by VIT) as used during the main DST performed on the upper fan in well 14/10-5.

The company said, “Rockhopper’s board views the flow rates achieved as being commercially viable.” Further appraisal drilling is being progressed over the coming months to continue to define the extent of the Sea Lion resource.

The Ocean Guardian semisubmersible will now drill 14/10-6, third appraisal well in the Sea Lion discovery area and 4.5 km west of well 14/10-5.